The present technology relates to technical fields of an image pickup lens and an image pickup apparatus. Specifically, the present technology relates to technical fields of an image pickup lens and an image pickup apparatus that have a shooting angle of view from about 40° to about 90° and F number of 2.8 or smaller.
Various types of bright lenses exist, for example, that have a shooting angle of view from about 40° to about 90° and F number of 2.8 or smaller for an image pickup apparatus with interchangeable lenses. As such a type of lens, a Gauss lens is widely known (for example, see Japanese Unexamined Patent Application Publication Nos. H06-337348 and 2009-58651 (JP H06-337348A and JP 2009-58651A)).
The Gauss lens has a configuration in which a convex lens and a concave lens are arranged symmetrically with an aperture stop in between. In the Gauss lens, whole of the lens system or part of lens groups travels along an optical axis at the time of focusing operation.
In recent years, digital cameras with interchangeable lenses have been rapidly in wide use. In particular, it has been possible to shoot moving images with the use of the image pickup apparatus with interchangeable lenses. Therefore, a lens suitable not only for shooting still images but for shooting moving images is desired. Accordingly, it is necessary to allow the lens group used for performing focusing operation to travel at high speed in accordance with rapid movement of a subject when shooting moving images.
The Gauss lenses disclosed in JP H06-337348A and JP 2009-58651A are each configured to allow whole of the lens system to travel along an optical axis at the time of focusing operation.
In a case where focusing operation is performed through allowing whole of the lens system to travel at high speed for shooting moving images in such a manner, weight of the focus lens group used for performing the focusing operation is increased. Therefore, an actuator for allowing the focusing lens groups to travel becomes large, and disadvantageously, a lens barrel becomes large.
On the other hand, an image pickup lens disclosed in Japanese Unexamined Patent Application Publication No. 2012-68448 (JP 2012-68448A) adopts rear-focus scheme. In the image pickup lens disclosed in JP 2012-68448A, a most-image-sided lens group is used as a focusing lens group, and thereby, focusing operation is achieved at high speed.
However, refractive power of the focusing lens group is set small in order to suppress variation in aberration during the focusing operation, and it is necessary to enlarge a traveling range of the focusing lens group accordingly. Therefore, an exit pupil becomes long, which disadvantageously prevents reduction in total length of the lens.